Influence of carbon characteristics on Sb/carbon nanocomposites formation and performances in Na-ion batteries

Abstract

The impact of carbon characteristics (structure, porosity and surface chemistry) on the Sb/Carbon composites formation and electrochemical performances in Na-ion batteries is investigated herein. Mesoporous and non-porous hard carbon heated at different temperatures were used to support Sb nanoparticles prepared via a ball-milling/thermal reduction synthesis approach. The mesoporous carbon presenting higher surface area and oxygen functional groups induce the formation of small Sb nanoparticles (<5 nm) well dispersed in the carbon network. For the hard carbon, the increase in the annealing temperature from 1100 to 1500 °C leads to more organized structure but lower porosity and surface functionalities having as consequence the increase of Sb nanoparticle size and the particle agglomeration. The best electrochemical performances vs. Na were achieved for hard carbon/Sb composite treated at 1100 °C which combines several advantages like dispersed Sb nanoparticle, low surface area and good conductivity (360 mAh g−1 after 200 cycles). Regarding the long-term capacity retention, for all materials a drastic decay was observed starting to 300 cycles and associated to the Sb particle size agglomeration and growth during repeated charge/discharge cycles and amorphization of Sb particles as demonstrated by post-mortem analyses.